Circuit breaker



NOV. 21, 1933. w n- 1,936,492

CIRCUIT BREAKER Filed March 3, 1931 2 Sheets-Sheet 1 F76. J 1 F76- I?INVENTOR George E. Whitehead "BY 11 ATTORNEY N 1933- s. E. WHITEHEAD CIRCUIT BREAKER Filed March 3, 1931 2 Sheets-Sheet 2 INVENTOR ATTo R16Patented Nov. 21, 1933 'UNlITEfi STATES PATENT O'FFICE CIRCUIT BREAKERGeorge Ethelbert Whitehead, Cardiff, South Wales Claims. (Cl. -150) Thisinvention relates to switches or circuit breakers intended moreespecially for breaking circuits carrying relatively heavy currents.

In the switch or circuit breaker according to the invention oil ispumped, preferably under appreciable pressure, upon and over thesurfaces of separating contacts. Preferably the pumping of the oil iseffected completely automatically by the opening movement of the switchor circuit breaker and after the contacts have separated a predetermineddistance. One of the contacts is preferably hollow in order that the oilmay be pumped through it. Preferably also the co-operating contacts areenclosed in an arc-quenching chamber which comprises an insulating tubecoaxial with said contacts and having an internal cross-sectional areaonly slightly greater than the cross-sectional area of the contacts,through which tube the oil is caused to pass under considerablepressure. Preferably also said insulating tube is adapted to move so asto follow up the separating contact.

The moving contacts may be carried by an insulating crosshead adapted toslide on guide rods,

or on some of said guide rods, in the lower end of the main casing, saidcrosshead being star-shaped or of open-work but rigid formation so thatit can move down readily in the oil to permit the switch or circuitbreaker to open rapidly. The contacts may be insulatingly mounted in ametal crosshead. The crosshead may be carried on a central operating rodwith an interposed spring if the contacts are of the butt type.

The arc-quenching tubes of insulating material may be carried on anothercrosshead, or between 9. pair of further crcssheads axially displacedfrom one another. In the latter case, one of the pair of crossheads isof star-shaped or open-work for nation, whilst the upper one constitutesa piston adapted to operate in the main casing, said pair of crossheadsbeing rigidly connected together by means, for example, of metal tubesadapted to slide upon the aforesaid guide rods, or upon some of them.The operating or pull rod of the crosshead carrying the moving contactsslides freely through the upper crosshead or pair of crossheads but hasa crosspin or other stop arrangedto engage the upper crosshead or one ofthem when the co-operating contacts have opened a predetermined distanceshorter than the full separation whereby to cause the oil in the case ofthe main casing to be pumped up with considerable pressure and velocitythrough the insulating arc-quenching chambers or tubes and over thesurfaces of the co-operating contacts to the upper part of the maincasing. The invention contemplates an arrangement in which the parts areso proportioned as to their dimensions and movements that a displacementof at least per cent.

of the total oil is brought about when the switch 60 or circuit breakeris opened.

To enable the arc-quenching chambers and the moving contacts to beraised to reclose the switch or circuit breaker, an externally operableelevat ing member adapted for vertical movement may be provided with alatch for normally retaining the moving contacts and insulating tubes intheir upper position, which latch is adapted to be re- 1 eased when theswitch or circuit breaker is tripped, throw-off springs for the movingcontacts being conveniently located around the operating or pull redwhilst springs located around the guide rods may be used for urging thepiston to its lower position when released, in addition to or in placeoi the aforesaid pin or stop on the operating rod of the movingcontacts.

To reclose the switch or circuit breaker it is merely necessary to movedown the elevating member until the catch thereon engages the operatingor pull rod of the moving contacts and thus 30 to raise the elevatingmember again.

To enable the invention to be clearly understood and carried into effectit will now be described with reference to the accompanying drawings inwhich Fig. l is a sectional elevation of a single pole, double breakswitch or circuit breaker in accordance with the invention,

Fig. 1a is an elevation of the upper portion of the switch shown in Fig.l as viewed from the right,

Fig. 2 is a horizontal section on the line 22, Fig. 1,

Fig. 3 is a horizontal section on the line 33, Fig. 1, and

Fig. 4 is a horizontal section on the line 4-4, Fig. 1.

Referring first to Fig. l of the drawings, 1 are the fixed contactswhich may be solid and are mounted on stems 3 carried in the top 4 of amain casing 8. The stems 3 are preferably closely shrouded with solidinsulation 5 which may be moulded thereon.

The moving contacts 2 are preferably tubular as shown, although this isnot essential. Said contacts 2 are mounted in a metal bridge 6 which isconventiently of star shape or other openWork formation. The top 4 hasperforations through which extend guide rods '7 fixed within the maincasing 8. Said casing 8 may consist of metal,

and may be lined with insulating material 9 and provided with a floor10, also of insulating material, to which the guide rods 7 may besecured. The crosshead or bridge 6 carrying the movable contacts 2 ismoved toward and away from the top 4 by means of a rod 11, a spring 12being introduced between a flange 11 on the rod 11 and the lower side ofthe crosshead 6 in the case of butt type or other non-resilientcontacts, such as those shown, so that the requisite contact pressurecan be obtained without undesirably straining the switch actuatingmechanism,

Two further crossheads are slidable upon the guide rods '7, namely, alower cross-head 13, which is of star or other openwork formation andmay be similar to the bridge or crosshead 6, whilst the upper crosshead14 is in the form of a disc so that it can act as a pump piston withinthe lining 9 of the main switch or circuit breaker casing. Thecrossheads 13 and 14 are rigidly held together by means of nuts 15engaging spacing tubes 16 which extend between said crossheads and areadapted to slide upon the guide rods 7.

The upper crosshead 14 is provided for example with ears 17' to whichmay be attached pull rods 18 whereby the crossheads 13 and 14 may beraised. Tubes of insulating material 17, which may consist of hardinsulating materials such as those known under the registered trademarksBakelite and Lorival, extend through and between the crossheads 13 and14. These tubes 17 extend, as shown, slightly above and below thecrossheads 14 and 13 respectively.

In Fig. 1 the switch or circuit breaker is shown with the parts in theopen or tripped position. In order to close the circuit breaker it isnecessary to raise the pull rods 18 and the main operating rod 11 untilthe moving contacts 2 firmly engage the fixed contacts 1.

The rod 11 and pull rods 18 may be raised by any suitable means, themeans shown in Figures 1 and 1 being constructed as follows:

The guide rods 7 extend through the top 4 of the casing and areconnected adjacent their upper ends by a crosshead 7. The rod 11 and thepull rods 18 are slidable through openings in the top 4. The rod 11 isalso slidable through the crosshead 7 and below said cross head carriesa cross bar 11, the ends of which extend, respectively, throughlongitudinal slots 18' in the pull rods 18.

A handle 11 is secured to the upper end of the rod 11 whereby said rodmay be raised.

A pair of hooks 7 each having a beveled nose 7 are pivoted on the lowerside of the crosshead '7 and are adapted, when the rod 11 is raised, toengage the cross bar 11' and hold said rod in its raised position. Alink 7 is connected to the hooks "I for rocking said hooks and therebydisengaging them from the cross bar 11.

When the rod 11 is raised by its handle 11 said rod will raise thebridge 6 and the cross bar 11, by engagement with the upper ends of theslots 18' of the pull rods 18, will raise said rods and with them thecrossheads 13 and 14. When the cross bar llcontacts with the bevelednoses 7 of the hooks 7 said hooks will be rocked out of the path of saidcross bar and will thereafter rock back beneath the cross bar to holdthe rod 11 and pull rods 18 in their raised position and the movablecontacts 2 in engagement with the fixed contacts 1. By pulling on thelink 7 (to the right in Fig. 1a) the hooks 7 may be disengaged from thecross bar 11 to permit the rod 11 and pull rods 18 to move downwardly.

Coiled springs 19 upon the guide rods '7 between the top 4 and crosshead14 serve to force the crossheads 13 and 14 and tubes 17 downwards whenthe pull rods 18 and actuating rod 11 are released.

The stems 3 have sockets 20 in their upper ends in which the circuitterminals 21 are frictionally held.

The casing 8-9 is adapted to be substantially filled with oil, and itwill be readily understood that, upon the tripping of the switch orcircuit breaker by the release of the rods 11 and 18, the crosshead 6carrying the moving contact 2 will move down comparatively rapidly inthe oil since said crosshead is of open formation, that is to say is soshaped that it cannot act like a pump piston as does the crosshead 14.The latter also moves down, but a slower speed owing to the fact thatduring its movement it will displace the body of oil which is containedin the main casing beneath the crosshead or piston 14. The downwardmovement of the latter due to the powerful springs 19 causes oil to beforced with considerable pressure and at considerable velocity upwardsthrough the tubular moving contacts 2 and also around the latter intothe lower ends of the tubes 17 which constitute arc quenching chambers.The oil passes up through the tubes 1'7, around the fixed contacts 1, tothe upper side of the piston crosshead 14. The parts are preferably soproportioned that about 60 per cent. of the total volume of oil used inthe circuit breaker is displaced in the manner just above described eachtime the switch or circuit breaker is tripped. It will be observed thatthe internal diameter of the tubes 17 constituting the arc quenchingchambers is only relatively slightly greater than the external diameterof the contacts 1 and 2, so that the oil must flow over said contacts ata relatively high velocity, thereby effectively cooling them whilsttending effectively to quench the arc.

In some cases it may be convenient to provide a stop 22 on the actuatingrod 11, adapted to engage the crosshead 13 when the main contacts haveseparated a part of the full distance so that the rod 11 in its downwardmovement may assist in moving the piston crosshead 14.

In Fig. 3 balls 60 are shown between the cooperating contacts 1 and 3.

It will be understood that various modifications of the circuit breakersshown in the drawings may be made without departing from the scope ofthe invention.

Having now particularly described and ascertained the nature of my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:--

1. An electric oil switch comprising an oilcontaining casing, an oilbarrier extending across said casing, a tubular arc quenching chamber ofinsulating material in said casing and extending through said barrier,said chamber being always at least partly immersed in the body of oil insaid casing and open at both ends, a pair of cooperating contactsextending, respectively, into the opposite ends of said chamber andmovable relatively to one another longitudinally of said chamber to makecontact in said chamber and forming with said chamber at all times afree oil channel from end to end of said chamber, and means permitting arelatively rapid separating movement between said contacts, said barrierbeing operable substantially independently of the Separating movement ofsaid contacts to cause a considerable quantity of oil to flow underpressure through said channel during the separating movement of saidcontacts.

2. Anelectric oil switch comprising an oil-containing casing, a tubulararc quenching chamber of insulating material in said casing, saidchamber being open at both ends and always at least partlyimmersed inthe body of oil in said casing, means for moving said chamberlongitudinally of said casing, a pair of co-operating contactsextending, respectively, into the opposite ends of said chamber andmovable relatively to one another and to said chamber longitudinally ofsaid chamber, said contacts forming at all times with said chamber afree oil channel through the lat 'ter from end to end, means for causinga short rapid separation of said contacts, and means operable by theseparation of said contacts for causing the flow of a considerablequantity of oil under pressure through said channel during theseparating movement of said contacts.

3. An electric oil circuit breaker comprising an oil containing casing,a tubular arc quenching chamber of insulating material movablelongitudinally of said casing, said chamber being open at both ends andalways at least partly immersed in the body of oil in said casing, meansfor moving said chamber longitudinally of said casing, a pair ofcooperating contacts extending, respectively, into the opposite ends ofsaid chamber and movable relatively to one another and to said chamberlongitudinally of said chamber, said contacts forming at all times withsaid chamber a free oil channel through the latter, means permittingarelatively rapid separating movement between said contacts, and meansassociated with the said chamber and operable by the movems ment of thelatter during the separation of cooperating contacts extending,respectively, into the opposite ends of said chamber and movablerelatively to one another and to said chamber longitudinally of saidchamber and forming with said chamber at all times a free oil channelthrough the latter, means permitting a relatively rapid separatingmovement between said con-- tacts, and pumping means associated withsaid chamber for causing a considerable quantity of such oil to flowunder pressure through said channel during the separating movement ofthe contacts.

5. An electric oil switch comprising a main oil tank, a tubulararcquenching chamber of insulating material always at least partly immersedin the body of oil in said tank and open at both ends, a pair ofcooperating contacts extending, respectively, into the opposite ends ofsaid chamber and movable relatively to one another longitudinally ofsaid arc, quenching chamber and forming with said chamber at all times afree oil channel through the latter, means permitting a relatively rapidseparating movement between said contacts, and means for causing aconsiderable quantity of the body of oil to flow under pressure throughsaid channel during the separating movement of said contacts, said meanscomprising a piston in the main oil tank and movable in a directionparallel with that of contact separation.

6. An electric oil switch comprising an oil-containing casing, a tubulararc quenching chamber of insulating material open at both ends andalways at least in part immersed in the body of oil said casing, a pairof cooperating, contacts extending, respectively, into the opposite endsof said chamber and movable relatively to one another longitudinallywithin said are quenching chamber to make contact therein and form ingwith said chamber at all times a free oil channel through the .latter,means permitting rapid initial separation of said contacts, pumpingmeans for causing a considerable quantity of oil to flow under pressurethrough said channel during the separating movement of said con tacts insaid chamber, and interconnecting means between the pumping means andthe movable contact for first permitting the movable contact to moveindependently of said pumping means and thereafter causing said movablecontact to move with pumping means.

'7. An electric oil s vitch comprising an oil-containing casing, atubular are quenching chamber movable longitudinally of said casing,said chamber being open at both ends and always at least in partiinlnersed in the body of oil in said casing, a fixed contact memberextending into one end of said chamber, a cooperating contact memberextending into the other end of said chamber and movable therein toengage said fixed contact member, said contacts being of smallercross-section than the internal cross-section of said tubular chamber toprovide at all times a free oil channel through said chamber, and meansfor causing said chamber to follow the movement of said movable contact.

8. An electric oil switch comprising an oilcontaining casing, a tubulararc quenching chamber of insulating material movable longitudinally ofsaid casing, said chamber being open at both ends and always at least inpart immersed in the body of oil in said casing, a fixed contactextending into one end of chamber, a carrier stem for said contact whichstem is shrouded in solid insulation, a cooperating movable contactextending into the other end of said chamber, a carrier l. ember forsaid movable contact, said carrier members and contacts being of smallercross-section than the internal cross section of said chamber to provideat all times a free oil channel through said chamber, and means forcausing said chamber to follow the movement of said movable contact.

9. An .ectric oil switch, comprising an oilcontaining casing, tubulararc quenching chair "er of insulating material open at both ends andalways at least in part immersed in the body of oil in said casing, afixed contact extending into one end or" said chamber, a carrier stemfor said contact which stem is shrouded in solid insulation, aJo-operating movable contact extending into the other end of id chamber,a carrier member for said movable contact, said co-operating contactsbeing of smaller cross-section than the internal cross-5e tion. of saidchamber to provide at all times a tree oil channel through said chamber,supporting means for said chamber, said supporting means being movablein said casing for causing a considerable part of the body of oil toflow under pressure through said chamber during separation of saidcontacts, and means for moving said supporting means longitudinally 0said casing.

10. An electric oil switch, comprising a main oil tank, a pump pistonmovable in said tank, a tubular arc quenching chamber of insulatingmaterial extending through said piston, said chamber being open at bothends and always at least in part immersed in the body of oil in saidtank, a fixed contact member extending into one end of said chamber, asecond movable contact member extending into the other end of saidchamber, said contact members being of smaller crosssection than theinternal cross-section of said chamber to provide a free oil channelthrough said chamber, spring means normally urging said piston in thedirection of separation of saidmoving contact, and trippable latchingmeans for holding said piston against said spring means when the contactmembers are engaged.

11. An electric oil switch, comprising a main oil tank, a pump pistonmovable in said tank, a tubular arc quenching chamber of insulatingmaterial extending through and carried by said piston, said chamberbeing open at both ends and always at least in part immersed in the mainbody of oil in said tank, a fixed contact member extending into one endof said chamber, a second contact member extending into the other end ofsaid chamber and movable into and out or engagement with the first-namedcontact member, means for moving said second contact member intoengagement with the fixed contact member, said contact members being ofsmaller crosssection than the internal cross-section of said chamber toprovide a free oil channel through said chamber, spring means normallyurging said piston in the direction of separation of said moving contactmember, spring means normally urging the movable contact member awayfrom the fixed contact member, and trippable latching means for holdingsaid piston against the first named spring means when the contactmembers are in engagement and for retaining said movable contact memberagainst the second named spring means and in engagement with said fixedcontact member, said second named spring means tending, when the pistonand the movable contact member are in the latched positions, to movethemovable contact member in advance of the piston and thereby cause aquick separation of said contact members while oil is pumped by thepiston through the oil channel in the arc quenching chamber.

12. An electric oil switch, comprising a fixed oil-containing pumpcylinder, a pump piston movable in said cylinder, a tubular arcquenching chamber of insulating material carried by and extendingthrough said piston and always at least in part immersed in the body ofoil in said cylinder, a fixed conductor stem extending into one end ofsaid chamber, a switch contact member on the end of said stem withinsaid chamber, a movable contact extending into the other end of saidchamber and movable toward and away from said fixed contact member, saidcontacts, stem and chamber affording a free oil passage through saidchamber, an actuating rod for said movable contact, said rod beingmovable relatively to said pump piston parallel to the direction ofmovement of the latter, spring means biassing said movable contact awayfrom said fixed contact, spring means biassing said pump piston in thedirection of separation of said contacts, latching means engageable withsaid actuating rod for holding said contacts together and holding thepump piston in opposition to its spring biassing means, and trippingmeans for releasing said latching means.

13. An electric oil switch comprising an oilcontaining casing, an oilbarrier across said casing, a tubular arc quenching chamber ofinsu1ating material extending through said barrier and always at leastpartly immersed in the body of oil in said casing and open at both ends,a pair of cooperating contacts extending, respectively, into theopposite ends of said chamber so as to make contact therein and movablerelatively to one another and to said chamber longitudinally of saidchamber, said contacts forming at all times with said chamber a free oilchannel through the latter from end to end, means for causing a shortrapid separation of said contacts, and means whose operation commenceswith but is otherwise substantially independent of the separation ofsaid contacts for causing the flow of a considerable quantity of oilunder pressure through said channel from one side of said barrier to theother during the separating movement of said contacts.

14. An electric oil circuit breaker comprising an oil containing casing,an oil barrier across said casing, a vertical tubular arc quenchingchamber of insulating material extending through said barrier, saidchamber being open at both ends and always at least partly immersed inthe body of oil in said casing, a pair of co-operating contactsextending, respectively, into the opposite ends of said chamber andmovable relatively to one another and to said chamber longitudinally ofsaid chamber so as to make contact therein, said contacts forming at alltimes with said chamber a free oil channel through the latter, meanspermitting a relatively rapid separating movement between said contacts,and means associated with said chamber and operable at least 120 in partindependently of the movement of the contacts during their separationfor compressing the main body of oil and causing a large proportion ofit to flow under pressure upwards through said channel from the lower tothe upper side of 125 said barrier.

15. An electric oil switch comprising an oilcontaining casing, an oilbarrier across said casing, a tubular arc quenching chamber ofinsulating material extending through said barrier, said chamber beingopen at both ends and always at least partly immersed in the body of oilin said casing, a pair of co-operating contacts extending, respectively,into the opposite ends of said chamber so as to make contact therein andmovable relatively to one another and to said chamber longitudinally ofsaid chamber and forming with said chamber at all times a free oilchannel through the latter, means permitting a relatively rapidseparating movement between said contacts, and a pump piston within thecasing movable substantially independently of the separating movement ofsaid contacts for causing a considerable quantity of oil to flow underpressure through said channel during the separating 145 movement of thecontacts.

GEORGE ETHELBERT WHITEHEAD.

